Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 191024
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
624 AM EDT TUE MAY 19 2015

.SYNOPSIS...
ISSUED AT 120 AM EDT TUE MAY 19 2015

MUCH COOLER AIR WILL CONTINUE TO OVERSPREAD THE AREA TODAY BEHIND
A COLD FRONT. CLOUDS WILL INCREASE THIS MORNING...WITH SKIES
BECOMING PARTLY CLOUDY THIS AFTERNOON. HIGH TEMPERATURES THIS
AFTERNOON ARE EXPECTED TO RANGE FROM THE LOWER 50S ACROSS
SOUTHWEST LOWER MICHIGAN TO AROUND 60 ACROSS NORTHWEST OHIO. A
RIDGE OF HIGH PRESSURE WILL SETTLE ACROSS THE WESTERN GREAT LAKES
REGION TONIGHT PROVIDING DIMINISHING WINDS...AND ALLOWING
LOW TEMPERATURES TONIGHT TO RANGE FROM THE MID 30S ACROSS
SOUTH CENTRAL LOWER MICHIGAN...TO THE UPPER 30S AND LOWER 40S ACROSS
MUCH OF NORTHERN INDIANA AND NORTHWEST OHIO. SOME PATCHY FROST IS
POSSIBLE LATE TONIGHT INTO EARLY WEDNESDAY MORNING ACROSS MAINLY
EXTREME NORTHEAST INDIANA AND SOUTH CENTRAL LOWER MICHIGAN.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM EDT TUE MAY 19 2015

BRUNT OF LOW LEVEL COLD ADVECTION WILL CONTINUE TO OVERSPREAD THE
LOCAL AREA THIS MORNING AS TIGHTLY PACKED BAROCLINIC ZONE DROPS
SOUTHEAST. COLD ADVECTION STRATOCU IS CURRENTLY ENTERING FAR
NORTHWEST PORTIONS OF THE AREA AS OF 07Z AND GIVEN PROGRESSION OF
STRONGEST COLD ADVECTION...WOULD EXPECT LOW CLOUDS TO OVERSPREAD
APPROXIMATELY NORTHWEST HALF OF THE AREA BY DAYBREAK...AND THEN
ACROSS MOST OF THE FORECAST AREA FOR THE REMAINDER OF THE AM HOURS.
GRADUALLY EXPECTING THESE LOW CLOUDS TO DIMINISH THIS AFTERNOON DUE
TO DIURNAL WARMING...INCREASING LOW LEVEL SUBSIDENCE...AND
INCREASINGLY DIVERGENT LOW LEVEL FLOW ACROSS SOUTHERN LAKE MICHIGAN.
HAVE GENERALLY FAVORED THE COOL SIDE OF GUIDANCE VALUES TODAY GIVEN
EFFECTS FROM STRATOCU AT LEAST THROUGH EARLY AFTERNOON...AND ALWAYS
SOME CONCERN WITH FRONTAL/SUBSIDENCE INVERSION THAT DURATION COULD
PROLONG A BIT FROM CURRENT FORECAST...ESPECIALLY ACROSS SOUTHEAST
HALF OF THE AREA THIS AFTERNOON. HIGHS SHOULD RANGE FROM AROUND 50
ACROSS THE FAR NORTHWEST TO AROUND 60 OR LOWER 60S FAR
SOUTHEAST...SOME 10 TO 15 DEGREES BELOW NORMAL FOR THE DATE. STEEP
LOW LEVEL LAPSE RATES WILL RESULT IN BRISK WINDS WITH SOME GUSTS TO
20 MPH THIS AFTERNOON.

WINDS TO DIMINISH QUICKLY THIS EVENING AS LAKE ENHANCED LOW LEVEL
ANTICYCLONE SETTLES INTO THE AREA. SKIES SHOULD ALSO BECOME MOSTLY
CLEAR EARLY IN THE EVENING SETTING UP A VERY COOL NIGHT. HAVE
MAINTAINED COLDEST MINS IN THE MID 30S ACROSS THE FAR NORTH GIVEN
ORIENTATION OF LOW LEVEL BAROCLINIC ZONE...WITH THE POTENTIAL OF AT
LEAST SOME PATCHY FROST. CONFIDENCE IN FROST IS STILL SOMEWHAT LOW
HOWEVER GIVEN EXPECTATION OF SOME INCREASING HIGH CLOUDS OVERNIGHT
AS NEXT SOUTH CENTRAL CANADIAN VORT MAX BEGINS TO ENTER GREAT LAKES
CONFLUENCE ZONE.

&&

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 349 AM EDT TUE MAY 19 2015

COOL AND QUIET WEATHER TO PERSIST THROUGH THE END OF THE WEEK WITH
GREAT LAKES REMAINING UNDER INFLUENCE OF NW FLOW AND GENERAL
SUBSIDENCE ON UPWIND SIDE OF PERSISTENT NEGATIVE HEIGHT ANOMALY OVER
QUEBEC. CONFLUENCE ALOFT AND COLD GREAT LAKES WILL FURTHER SUPPORT
SURFACE HIGH PRESSURE OVER THE REGION. ONE WEAK SHORTWAVE DOES EJECT
OUT OF THE SOUTHWEST CONUS AND INTERACT WITH SUBTLE NORTHERN STREAM
VORT MAX LATE TOMORROW. MID/UPPER LEVEL SUPPORT IS DECENT AND COULD
BE SOME ENHANCED FGEN IN RIGHT ENTRANCE REGION OF UPPER LEVEL JET
BUT FORECAST SOUNDINGS INDICATE VERY DRY AND STABLE LOWER LEVELS.
MOISTURE CONVERGENCE REMAINS LOCKED TO OUR SOUTH WITH GENERALLY
NORTHERLY FLOW IN PLACE LOCALLY. WAVE WILL ALSO BE INCREASINGLY
SHEARED AS IT ZIPS EAST AND PREFER MORE SUBDUED QPF OF LATEST
GFS...NAM...AND GEM OVER THE 19.00Z ECMWF. INHERITED LOW CHANCE POPS
STILL SEEM APPROPRIATE AND ONLY MINOR CHANGES MADE.

OTHERWISE...NEXT CHANCE OF RAIN WILL NOT ARRIVE UNTIL EARLY NEXT
WEEK WHEN SOUTHWEST FLOW/THETA-E ADVECTION RETURN AHEAD OF NEXT
EJECTING WESTERN CONUS TROUGH. STOUT RIDGE EXPECTED TO DEVELOP AHEAD
OF THIS FEATURE AND NOT SURPRISINGLY...LATEST GFS HAS TRENDED
SLOWER...KEEPING US DRY UNTIL EARLY MONDAY. GIVEN RECENT POOR
PERFORMANCE OF MODEL CP SCHEMES/QPF IN WARM SECTORS WELL AHEAD OF
EJECTING TROUGH...PREFER A MORE SUBDUED POP FORECAST THAN
INITIALIZATION PROVIDES AND WILL HOLD BELOW LIKELY WORDING
THRESHOLDS. CERTAINLY THERE IS A CHANCE FOR RAIN DURING THE LATTER
HALF OF THE HOLIDAY WEEKEND BUT DO NOT WANT TO GIVE THE IMPRESSION
OF A GUARANTEED WASHOUT. TEMPS WILL ALSO SLOWLY MODERATE BACK TO
SEASONAL NORMS BY THE WEEKEND.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 613 AM EDT TUE MAY 19 2015

LOW LEVEL COLD ADVECTION ACROSS THE AREA WILL ALLOW STRATOCU DECK
TO EXPAND SOUTHEAST THIS MORNING. CIGS SHOULD BE HOVERING RIGHT
AROUND 3K FT WITH THIS DECK ALTHOUGH WILL CONTINUE TO MENTION
TEMPO CIGS IN THE 2500-3000 FT RANGE THROUGH 15Z OR 16Z.
INCREASING LOW LEVEL SUBSIDENCE AND DIURNAL EFFECTS SHOULD TEND TO
ERODE THIS DECK DURING THE MID AFTERNOON HOURS...WITH VFR
CONDITIONS THEN EXPECTED TO HOLD THROUGH THE REMAINDER OF THIS
FORECAST CYCLE. STEEP LOW LEVEL LAPSE RATES IN THIS COLD ADVECTION
PATTERN TO ALLOW SOME GUSTS TO AROUND 20 KNOTS TODAY. WINDS WILL
QUICKLY DIMINISH TONIGHT AS A LAKE MICHIGAN REINFORCED LOW LEVEL
ANTICYCLONE BEGINS TO BUILD INTO THE AREA...WITH JUST SOME
INCREASING HIGH CLOUDS TOWARD THE END OF THE PERIOD.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...BEACH HAZARDS STATEMENT UNTIL 4 PM CDT THIS AFTERNOON FOR INZ003.

MI...BEACH HAZARDS STATEMENT UNTIL 5 PM EDT THIS AFTERNOON FOR MIZ077.

OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ043-
     046.

&&

$$

SYNOPSIS...MARSILI
SHORT TERM...MARSILI
LONG TERM...AGD
AVIATION...MARSILI


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